How to estimate or calculate Tivoli Storage Manager TSM database size

To estimate space requirements for
the database, you can use the maximum number of files that can be
in server storage at one time or you can use storage pool capacity.

Estimating Tivoli Storage Manager database size

Consider using
at least 25 GB for the initial database space. Provision file system
space appropriately. A database size of 25 GB is adequate for a test
environment or a library-manager-only environment. For a production server supporting
client workloads, the database size is expected to be larger. If you
use random-access disk (DISK) storage pools, more database and log
storage space is needed than for sequential-access storage pools.

The maximum size of the Tivoli Storage
Manager database
is 4 TB. For estimating Database consider the following example.

Estimating database space requirements based on the number of files

If you can estimate the maximum number
of files that might be in server storage at a time, you can use that
number to estimate space requirements for the database.

To estimate space requirements
for the database based on the maximum number of files in server storage,
use the following guidelines:

Additional space is required for database optimization to support
varying data-access patterns and to support server back-end processing
of the data. The amount of additional space is equal to 50% of the
estimate for the total number of bytes for file objects.

In the following example for a single client, the calculations
are based on the maximum values in the preceding guidelines. The calculations
do not take into account the possible use of file aggregation. In
general, aggregating small files reduces the amount of required database
space. File aggregation does not affect space-managed files.

Calculate the number of file
versions:

Calculate the number of backed-up files: As
many as 500,000 client files might be backed up at a time. Storage
policies call for keeping up to three copies of backed up files:

500,000 files x 3 copies = 1,500,000 files

Calculate the number of archive files. As
many as 100,000 client files might be archived copies.

Calculate the number of space-managed files. As many as 200,000 client files might be migrated from client
workstations.

Using 1000 bytes per file, the total amount of database
space required for the files that belong to the client is 1.8 GB:

Calculate the number of cached copies. Caching
is enabled in a 5 GB disk storage pool. The high and low migration
thresholds of the pool are 90% and 70%. Thus, 20% of the disk pool,
or 1 GB, is occupied by cached files.

If the average file size
is about 10 KB, approximately 100,000 files are in cache at any one
time:

100,000 files x 200 bytes = 19 MB

Calculate the number of copy storage-pool files. All primary storage pools are backed up to the copy storage
pool:

(1,500,000 + 100,000 + 200,000) x 200 bytes = 343 MB

Calculate the number of active storage-pool files. All the active client-backup data in primary storage pools
is copied to the active-data storage pool. Assume that 500,000 versions
of the 1,500,000 backup files in the primary storage pool are active:

500,000 x 200 bytes = 95 MB

Calculate the number of deduplicated files. Assume
that a deduplicated storage pool contains 50,000 files:

50,000 x 200 bytes = 10 MB

Based on the preceding calculations, about 0.5 GB of additional
database space is required for the client’s cached files, copy storage-pool
files, and active-data pool files, and deduplicated files.

Calculate the amount of additional
space that is required for database optimization. To
provide optimal data access and management by the server, additional
database space is required. The amount of additional database space
is equal to 50% of the total space requirements for file objects.

(1.8 + 0.5) x 50% = 1.2 GB

Calculate the total amount of database
space that is required for the client. The total is approximately
3.5 GB:

1.8 + 0.5 + 1.2 = 3.5 GB

Calculate the total amount
of database space that is required for all clients. If
the client that was used in the preceding calculations is typical
and you have 500 clients, for example, you can use the following calculation
to estimate the total amount of database space required for all clients:

500 x 3.5 = 1.7 TB

In the preceding examples,
the results are estimates. The actual size of the database might differ
from the estimate because of factors such as the number of directories
and the length of the path and file names. Periodically monitor your
database and adjust its size as necessary.

During normal operations, the Tivoli® Storage
Manager server might
require temporary database space. This space is needed for the following
reasons:

To hold the results of sorting or ordering that are not already
being kept and optimized in the database directly. The results are
temporarily held in the database for processing.

To give administrative access to the database through one of the
following methods:

A DB2® open database connectivity
(ODBC) client

An Oracle Java™ database
connectivity (JDBC) client

Structured Query Language (SQL) to the server from an administrative-client
command line

Consider using an additional 50 GB of temporary space
for every 500 GB of space for file objects and optimization. See the
guidelines in the following table. In the example used in this topic,
a total of 1.7 TB of database space is required for file objects and
optimization for 500 clients. Based on that calculation, 200 GB is
required for temporary space. The total amount of required database
space is 1.9 TB.

Database size

Minimum temporary-space requirement

< 500 GB

50 GB

≥ 500 GB and < 1 TB

100 GB

≥ 1 TB and < 1.5 TB

150 GB

≥ 1.5 and < 2 TB

200 GB

≥ 2 and < 3 TB

250 - 300 GB

≥ 3 and < 4 TB

350 - 400 GB

Estimating database space requirements based on storage pool capacity

To estimate database space requirements
based on storage pool capacity, use a ratio of 1 - 5%. For example,
if you require 200 TB of storage pool capacity, the size of your database
is expected to be 2 - 10 TB. As a general rule, make your database
as large as possible to prevent running out of space. If you run out
of database space, server operations and client-store operations can
fail.

Database space required when running database operations

The database manager of the Tivoli® Storage
Manager server manages
and allocates system memory and disk space for the database. The amount
of database space that the system requires depends on the amount of
system memory that is available and the server workload.

For example, expiration processing can use a large amount of database
space. If there is not enough system memory in the database to store
the files identified for expiration, some of the data is allocated
to temporary disk space. During expiration processing, if a node or
file space is selected that is too large to process, the database
manager cannot sort the data.

To run database operations, consider adding more database space
for the following scenarios:

The database has a small amount of space and the server operation
that requires temporary space uses the remaining free space.

The file spaces are large, or the file spaces have a policy assigned
to it that creates many file versions.

The Tivoli Storage
Manager server
must run with limited memory.

An out of database space error is displayed when
you deploy a Tivoli Storage
Manager V6
server.

Do not alter the DB2 software that is installed
with IBM® Tivoli Monitoring for Tivoli Storage Manager installation
packages and fix packs. Do not install or upgrade to a different version,
release, or fix pack of DB2 software because doing so can damage the
database.

The database manager and temporary space

The Tivoli Storage
Manager server
database manager manages and allocates system memory and disk space
for the database. The amount of database space you require depends
on the amount of system memory available and the server workload. Also Read: TSM Storage Pool Concepts (V7 Revised)

The database manager sorts data in a specific sequence, as per
the SQL statement that you issue to request the data. Depending on
the workload on the server, and if there is more data than the database
manager can manage, the data (that is ordered in sequence) is allocated
to temporary disk space. Data is allocated to temporary disk space
when there is a large result set. The database manager dynamically
manages the memory used when data is allocated to temporary disk space.

For example, expiration processing can produce a large result set.
If there is not enough system memory on the database to store the
result set, some of the data is allocated to temporary disk space.
During expiration processing, if a node or file space are selected
that are too large to process, the database manager does not have
enough memory to sort the data.

To run database operations, consider adding more database space
for the following scenarios:

The database has a small amount of space and the server operation
that requires temporary space uses the remaining free space.

The file spaces are large, or the file spaces has a policy assigned
to it which creates many file versions.

The Tivoli Storage
Manager server
must run with limited memory. The database uses the Tivoli Storage
Manager server main
memory to run database operations. However, if there is insufficient
memory available, the Tivoli Storage
Manager server allocates
temporary space on disk to the database. For example, if 10G of memory
is available and database operations require 12G of memory, the database
uses temporary space.

An out of database space error is displayed when
you deploy a Tivoli Storage
Manager V6
server. Monitor the server activity log for messages related to database
space.